21445321 has 4 divisors (see below), whose sum is σ = 21653632. Its totient is φ = 21237012.

The previous prime is 21445247. The next prime is 21445327. The reversal of 21445321 is 12354412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21445321 - 2²¹ = 19348169 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21445292 and 21445301.

It is not an unprimeable number, because it can be changed into a prime (21445327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 104001 + ... + 104206.

It is an arithmetic number, because the mean of its divisors is an integer number (5413408).

Almost surely, 2^21445321 is an apocalyptic number.

It is an amenable number.

21445321 is a deficient number, since it is larger than the sum of its proper divisors (208311).

21445321 is a wasteful number, since it uses less digits than its factorization.

21445321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208310.

The product of its digits is 960, while the sum is 22.

The square root of 21445321 is about 4630.9093059571. The cubic root of 21445321 is about 277.8289624731.

Adding to 21445321 its reverse (12354412), we get a palindrome (33799733).

Subtracting from 21445321 its reverse (12354412), we obtain a palindrome (9090909).

The spelling of 21445321 in words is "twenty-one million, four hundred forty-five thousand, three hundred twenty-one".